Systems have been developed for locating utilities below ground at excavation sites and monitoring activities of earth working equipment at such sites. Examples of such systems are described in U.S. Pat. No. 5,198,800 (Tozawa et al 1993); U.S. Pat. No. 5,964,298 (Greenspun 1999); U.S. Pat. No. 6,119,376 (Stump 2000) and U.S. Pat. No. 6,282,477 (Gudat 2001). These systems are site specific.
When emergency response crews respond to a call there is a need for access to information regarding the proximity of utilities. For example, in the event of a fire, knowledge as to the proximity of high pressure gas lines or power lines is crucial. Equally important is knowledge as to the closest fire hydrant for supplying water to fight the fire. The situation rarely remains static. Depending upon wind conditions and fuel sources, the fire may rapidly progress in one of several directions. When this occurs, it is important that the emergency response crew be able to continually update information as to the presence of utilities in the path of the fire.